DA.KOTA AND NEBRASKA. 



97 



Skull of Oreodox gracilis. 



Length skull fr. summit of inion to end of nose, 

 Length lower jaw fr. back border to'inc. alv., 

 Length cranium from summit of inion to post- 

 orbital margin, . . . . 

 Breadth of cranium where narrowest, 

 Length face fr. post.-orb. margin to end of nose. 

 Breadth cranium where most convex on the 



parietals, .... 

 Height of occiput or inion, 

 Breadth of occiput at base, 

 Breadth of skull at zygomatic arches, 

 Breadth at the post-orbital arches. 

 Breadth of face at anterior orbital margins. 

 Breadth of face at upper first premolars. 

 Breadth of face above last molars. 

 Length of parietal crest, 

 Length of frontals in median line. 

 Length of nasals. 

 Breadth of snout between ends of frontal an 



gular processes, . 

 Vertical diameter of orbits, . 

 Transverse " " . 



Height of lower jaw at coronoid process, 

 " condyle, 

 " " " back of last molar, 



" " " second premolar. 



Breadth of do. obliquely back of last molar, 

 Length of symphysis of lower jaw, 

 Distance between the supra-orbital foramina. 

 Distance between the iufra-orbital " 



Length of hard palate, 

 Width of hard palate between first molars. 

 Length of the alveolar borders. 

 Length of the upper molar series, 

 " lower 



" " upper true molar series, 



" " lower 



Measurements of specimens in lines. 



54 

 51 



30 



11* 



30 



161 



18 



18i 



36 



24 



21 



11 



22 



19 



17 



19 



9 

 9 



9* 

 28 

 25 

 15 



8 

 20 

 14 



5 

 12i 



32 



25J 



24 



141 



15 



121 



161 

 19 



211 



8 9 10 11 12 



56 



31 



101 



30 



18 

 18 

 18J 

 36 

 26 

 22 

 101 101 



201 



19 



181 



51 

 12 



14 



21 

 19 

 171 



5^ 

 111 

 30 



25 



14 



25 

 19 

 91 



9 

 8 



8J 



14 



51 

 11 



27 

 26 

 15 



161 



40 

 29 

 25 



19 



19 J 



91 



9 



32 

 28 

 17 



5 

 14 



13 



18 



40 

 29 

 23 



27 

 20 

 20 



71 

 10 

 10 



18 

 20 



12 

 10 



19 



m 13 



28 

 23 

 11 

 22 



18 



71 



5 

 13 

 30 

 10 

 31 

 25 



14 



25 

 13 

 27 



23 



6 

 15 

 34 

 12 



29 



17 



23 



12; 



23 



6 

 13 

 31 

 10 



26 



15 



36 

 28 

 131 

 28 



21 



101 

 11 



6 



151 



111 



30 



18 



50 



28 

 26 

 16 

 10 

 21 

 14 



26 



17 



29 

 10* 



Ui 



18 



18 



36 



24 



19 



101 



21 



20 



17i 



9 



Si 

 28 J 

 24J 

 14 



71 



6 

 12 



25 i 

 25 

 14 

 151 



The teeth of Oreoclon gracilis are identical in form with those of 0. Gulhertsoni, 

 and are ordinarily distinguishable only by the size. In those specimens, however, in 

 which the teeth of the former are fully equal in size to those of smaller teeth of the 

 latter species, independently they would be undlstinguishable. 



The following table presents measurements of the upper teeth of Oreodon gracilis. 

 Those of the first and second series are taken from the same specimens as Nos. 2 and 

 3 of the preceding table, and exhibit the usual sizes. Tho.se of the third and fourth 

 series correspond with Nos. 6 and 10 of the preceding table, and present sizes greatly 

 in excess of the usual ones. Other specimens are at hand, exhibiting all gradations 

 of intermediate sizes, but none in a condition to give complete series of measurements. 

 The fifth series of tlie table gives measurements from a specimen of Oreodon Ctdbert- 

 soni with small teeth, previously indicated as No. 16 : 



13 



